Slotting cutter and inserts for same

ABSTRACT

The present invention is directed to an insert, a slotting cutter assembly and a method for machining a plurality of slots in a metallic alloy part. The insert may comprise a cutting edge, at least one primary radius, at least two secondary radii and a clearance angle. The cutting edge may form a narrow outer end at a tip of the insert and a larger width region at a distance inward from the narrow outer end. The clearance angle may extend rearward from the cutting edge. The slotting cutter assembly may comprise a plurality of inserts and a cutter body. The cutter body may comprise a plurality of retaining slots and a plurality of support portions. The retaining slot may be configured to receive the insert. The support portion may provide support for the insert.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to provisional application Ser. No.60/891,642, entitled “Slotting Cutter and Inserts for Same” by Donald R.Hughes, filed Feb. 26, 2007, which is hereby incorporated by reference.

BACKGROUND OF THE TECHNOLOGY

1. Field of Technology

The present disclosure relates to cutting tools, cutting inserts, andtechniques for machining metals and metallic alloys. The presentdisclosure more specifically relates to slotting cutters and cuttinginserts adapted for use with such cutters, and to techniques formachining metals and alloys using such cutting tools.

2. Description of the Background of the Technology

Slotting cutters are used in the metal working industry to machine fullor partial slots in a part piece. A typical slotting cutter comprises acircular cutter body, and one or more high speed steel (“HSS”), carbide,or ceramic cutting inserts. These inserts are positioned around theperiphery of the cutter body. The slotting cutter is attached to amachine spindle and rotated at speeds sufficient to remove material froma part piece when contact is made between the inserts and the partpiece. Slotting cutters can be right hand, left hand or neutral,depending upon the axial location of the inserts on the cutter body.

A major concern in the cutting tool industry is retention of cuttinginserts on the cutter body. The inserts must be securely and accuratelyfastened to the cutting tool body and also must be able to be quicklyinstalled and replaced. Secure and accurate attachment is especiallyimportant when ceramic inserts are used because cutting speeds in excessof 1000 surface feet per minute (“SFM”) are common and any slight insertmovement or inaccuracy in the location of the inserts in designs wheremultiple inserts are used can result in catastrophic failure. Theseinserts must be fully retained both axially and radially.

Another major concern in the cutting tool and machining industry is theavailability of machine time. Increased production may have a positivefinancial impact on production facilities. Personnel working in theindustry are continually looking for ways to improve machine throughputand thus improvements in machine production. These solutions can beaccomplished in a number of ways including improving performance on aparticular machine or switching production to a more efficient machinefrom a less efficient machine.

Parts such as turbine disks typically have been machined using atechnique known as broaching. Turbine disks are often found in variousturbine assemblies. Multiple turbine disks are located along the lengthof a turbine shaft and are used to connect the turbine blades to theturbine shaft. A typical slot machined in the turbine disk correspondsto the shape of the end of a turbine blade. The turbine blade may thenbe fit into the slot of the turbine disk thus securing the turbine bladeto the turbine disk. These turbine blades cause the turbine shaft torotate when a gas or liquid is passed over the blades.

The slot formed in the turbine disk is normally machined using abroaching technique. Broaching is a type of machining where a cuttingtool with a number of progressively increasing cutting edges is pushedor pulled over a machine surface to make a cut. For example, in turbinedisk manufacturing, a “Christmas tree” or “fir tree” shaped keyway mustbe cut on the periphery of the turbine disk to accept a correspondingshaped end of a turbine blade. These keyways have been typically cutusing broaching with a cutting tool that has progressively larger “firtrees” as the cut is made. Broaching is an extremely slow and costlymethod of machining. The broaches used to machine turbine diskstypically include broach segments to rough and finish a slot. Othertechniques have been attempted including grinding and wire electronicdischarge machine (“EDM”). The use of a slotting cutter may provide afaster and more efficient method of machining rough slots on a turbinedisk. Subsequent to machining the rough slots, the disk may be furthermachined to provide each of the slots with the shape required in thefinished turbine component. This shape may be quite complex. Althoughfinish machining may require the use of broaching, the rough slot ismachined much more quickly, and potentially more cost effective, giventhe increased production of a slotting cutter versus a broachingmachine.

Turbine disks are conventionally formed of nickel-based superalloys,such as Alloy 718 (UNS N017718) and Rene 95™ alloy. These nickel-basedsuperalloys are often referred to as high temperature alloys.Nickel-based superalloys are very difficult to machine due to theirhardness and abrasiveness, among other things. Metals are given amachinability rating which indicates the difficulty of machining thatmetal. A metal with a high machinability rating is much easier tomachine than a metal with a lower machinability rating. Generally, themachinability rating of a nickel-based superalloy is approximately 10%of the machinability rating of cold-rolled steel. Broaching hastypically been required to machine these alloys. Manufacturers ofturbine disks have been looking for a method to machine turbine disksmore quickly. What is needed is a less costly and more efficient methodfor machining turbine disks.

SUMMARY

In one general aspect, the present invention is directed to an insert, aslotting cutter assembly and a method for machining a plurality of slotsin a metallic alloy part. The insert may comprise a cutting edge, atleast one primary radius, at least two secondary radii and a clearanceangle. The cutting edge may form a narrow outer end at a tip of theinsert and a larger width region at a distance inward from the narrowouter end. The primary radius may be located at the tip of the insert.The two secondary radii may be located on opposite sides of the cuttingedge near a mounting portion of the insert. The clearance angle mayextend rearward from the cutting edge. The slotting cutter assembly maycomprise a plurality of inserts and a cutter body. The cutter body maycomprise a plurality of retaining slots and a plurality of supportportions. The retaining slot may be configured to receive the insert.The support portion may be disposed on one end of the retaining slot andmay provide support for the insert.

The method may include retaining a plurality of inserts within thecutter body of the slotting cutter and retaining the metallic alloy partin a part holder which is configured to move the metallic alloy part.The inserts may be fabricated from a ceramic material. The metallicalloy part may be a turbine disk. The slotting cutter may be operated tocause the cutter body to rotate about an axis. The part holder may bepositioned such that a proposed slot location on the metallic alloy partis placed in line with the plurality of inserts and at a height whichallows the plurality of inserts when cutting the metallic alloy part toform the depth of the slot. The part holder may be moved in a directionorthogonal to the axis of the cutter body such that the plurality ofinserts contacts the metallic alloy part as the metallic alloy partmoves orthogonal to the axis of the cutter body. A slot may be cutwithin the metallic alloy part with the plurality of inserts as themetallic alloy part moves orthogonally to the axis of the cutter body.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the novel articles described herein may bebetter understood by reference to the accompanying drawings in which:

FIG. 1A is a face view of an embodiment of a slotting cutter accordingto the present disclosure;

FIG. 1B is a side view of an embodiment of the slotting cutter of FIG.1A;

FIG. 1C is a perspective view of an embodiment of the slotting cutter ofFIG. 1A;

FIG. 2A is a view of an insert disposed within a rough slot of a turbinedisk looking along the axis of the turbine disk;

FIG. 2B is a view of a rough slot of the turbine disk looking along theaxis of the turbine disk;

FIG. 2C is a view of a finished slot of the turbine disk looking alongthe axis of the turbine disk;

FIG. 3 is a side view of a face of a cutter body;

FIG. 4 is an end view of the cutter body of FIG. 3;

FIG. 5 is a perspective illustration of the cutter body of FIG. 3;

FIG. 6A is a drawing of a cutting face of one embodiment of a cuttinginsert;

FIG. 6B is a top view of the cutting insert of FIG. 6A;

FIG. 6C is a left side view of the cutting insert of FIG. 6A;

FIG. 6D is a bottom view of the cutting insert of FIG. 6A;

FIG. 6E is a drawing of a cutting face of another embodiment of acutting insert;

FIG. 6F is a drawing of a cutting face of another embodiment of acutting insert;

FIG. 7 is a close-up of a side view of the cutting insert retained inthe cutter body by a wedge-like fastener; and

FIG. 8 is a close-up of a top view of the assembly of FIG. 7.

The reader will appreciate the foregoing details, as well as others,upon considering the following detailed description of certainnon-limiting embodiments of articles according to the presentdisclosure. The reader also may comprehend certain of such additionaldetails upon carrying out or using the articles described herein.

DETAILED DESCRIPTION OF THE INVENTION

According to various embodiments, the present invention is directed toinserts, a slotting cutter assembly and methods for machining slots inmetal and metallic alloy piece parts. This method may use a slottingcutter 100, as shown in FIGS. 1A-1C. FIG. 1A is a face view of anembodiment of the slotting cutter. FIG. 1B is a side view of anembodiment of the slotting cutter. FIG. 1C is a perspective view of anembodiment of the slotting cutter. The slotting cutter 100 may comprisea cutter body 102 and a drive assembly 123. In one embodiment, inserts104 may be used in the machining process which may be securely retainedwithin the cutter body 102. An important application where an embodimentof the present invention has proven useful is for machining of roughslots in disks used in aerospace turbine engines. These rough slots areeventually machined into finished slots which have a profile whichcorrespond to a shape on an end of a turbine blade. As discussedpreviously, the turbine blades can then be fit into the slots on theturbine disk.

The arrangement of the slotting cutter 100 along with a work piece, suchas a turbine disk 101, is shown in FIGS. 1A-1C. As can be seen in FIG.1A-1C, the slotting cutter 100 may comprise a cutter body 102. Thecutter body 102 may be mounted on a machine spindle so that the cutterbody 102 may be rotated about its axis 113. The axis 113 of the cutterbody 102 and the axis 117 of the turbine disk 101 may be arranged suchthat they are substantially orthogonal. The cutter body 102 may beconfigured to rotate about its axis 113. In various embodiments, thecutter body 102 may rotate in the counter clockwise direction, asindicated by the rotation arrow 103, as shown in FIG. 1A. In variousother embodiments, the slotting cutter may be configured to rotate inthe opposite direction (i.e., clockwise, as shown in FIG. 1A).

According to various embodiments, the turbine disk 101 may be retainedin a part holder 111. The part holder 111 may be a portion of a partholder assembly. The turbine disk 101 may generally be held in a fixedposition to allow the slotting cutter 100 to machine a slot in theturbine disk 101, and then may be rotated about its axis 117 to the nextposition where a slot may be machined. For example, the turbine disk 101may be rotated in an index fashion to each slot location once themachining of a slot is completed, whereas the slotting cutter 100 may berotated continuously to machine the slot. The turbine disk 101 may berotated in either direction about its axis 117. Once the turbine disk101 is rotated into position, the part holder 111 advances in a feeddirection, or x direction, as shown by the feed arrow 105 in FIG. 1A,through the cutter body 102 until the rough slot is completely cut inthe periphery of the turbine disk. Once the slot has been cut, the partholder 111 substantially returns to its initial position, and theturbine disk 101 is rotated into position for the cutting of the nextslot. The part holder 111 may be moved in any of an x direction (i.e.,the feed direction), a y direction, as illustrated by y arrow 107 inFIG. 1B, or in a z direction, as illustrated by z arrow 109 in FIG. 1A.The y direction may be used to accurately place the turbine disk 101 ina position relative to the cutter body 102 to have the slot machined inthe correct position on the turbine disk. The z direction may be used toset the height of the turbine disk 101 to set the depth of the slot tobe machined by the cutter body 102.

FIG. 2A is a view of an insert 104 disposed within a rough slot 116 ofthe turbine disk 101 looking along the axis 117 of the turbine disk 101.FIG. 2B is a view of a rough slot 116 without the insert 104. The roughslots 116 may have a profile substantially the same as the profile ofthe insert 104. As shown in FIG. 2C, which depicts a finished profile ofa turbine disk slot, the finished slots 115 may have a unique steppedshape, sometimes referred to as a “Christmas tree” or “fir tree” shape,which is difficult to machine. The machining of the rough slots 116 maybe accomplished more quickly if performed using a slotting cutter 100rather than a broach. A prior slotting cutter design had been proposedbut the design was shown to not be commercially viable. The priorslotting cutter design proved costly to produce and operate. The priorslotting cutter design required the use of more than one style or typeof cutting insert, which significantly increased operating costs. Forexample, a narrow insert may have been used to machine the full depth ofthe slot, and another wider insert may have been used to machine thefull width of the slot. Also, due to the nature of the earlier slottingcutter designs, a high level of care and accuracy was necessary wheninstalling inserts to insure proper location and lock-down. Someslotting cutters used in the industry employ a cartridge arrangement,where the insert is placed in a cartridge and the entire cartridge isthen held in the cutter body, to hold the inserts on the tool. Thesetypes of slotting cutters may potentially add substantial cost andsignificant complexity to the design.

According to various embodiments of the present invention, the methodused in slot cutting may be unique for at least the reason that it hasbeen shown to achieve fast and economical rough machining of slots 116in smaller turbine disks. Rough slots 116 may be formed in such disks tohave a depth in the range of ⅛ inch to ¾ inch and a width in the rangeof 3/32 inch to ½ inch. Generally, the rough slots may have a depth upto ¾ inch and a width up to ½ inch, but both the depth and the width ofthe slots 116 may vary. The inserts 104 must generally follow thedimensions of the rough slots 116. The inserts may be configured to cuta depth in the range of ⅛ inch to ¾ inch and a width in the range of3/32 inch to ½ inch. For example, in one embodiment, the inserts 104 maybe configured to cut a depth of ¾ inch and a width of ½ inch in therough slot 116.

FIG. 3 is a face view of an embodiment of the cutter body 102 accordingto the present disclosure. FIG. 4 is a side view of the same cutterbody. FIG. 5 is a perspective illustration of the same cutter body 102.The slotting cutter 100 may include the cutter body 102, which may bedisk-shaped and adapted to be rotated about its axis 113. A plurality ofcutting inserts 104 may be retained on the cutter body 102. As shown inFIG. 2, each insert 104 may have a shape similar to, but smaller than,the shape of the finished slot. Each of the inserts 104 may be retainedon the cutter body 102 by a wedge-like fastener 106. The inserts 104 maybe retained on the periphery of the cutter body 102. The inserts 104 maybe retained axially in the same position or in different positions. In apreferred embodiment, the inserts 104 are axially retained in the sameposition on the side of the cutter body 102 away from a drive motor. Thewedge-like fastener 106 may be secured to the cutter body 102 by a screw108. The screw 108 may extend through the wedge-like fastener 106axially into the cutter body 102. The screw 108 may be a double-actingscrew, where one end of the screw 108 has right-hand threads and theother end has left-hand threads, or the screw 108 may be any othersuitable type of screw.

In various embodiments, as shown in FIG. 2A, the inserts 104 may have acontinuous cutting edge 110 which may be formed to cut a smaller widthslot near the tip of the insert and a larger width slot at a distanceinward from the tip. The insert 104 may include a larger width region114 and a smaller width region 112. The cutting edge 110 may extendaround the periphery of the top insert 104, generally covering thesmaller width region 112 and the larger width region 114 of the insert.A mounting portion 118 of the insert 104 is shown in dotted lines andmay be accurately positioned on and secured to the cutter body 102 ofthe slotting cutter 100. In various embodiments, it may be apparent thatthe cutting insert's 104 stepped profile would cut out a rough form ofthe slot 116, which may then be further machined to provide the finishedslot profile 115 shown in FIG. 2C. The finished machining may beaccomplished with a broaching machine or any other suitable machiningprocess. Although the rough slot 116 shown in FIG. 2B is a rough slot116 which will eventually be machined to a finished slot 115 of the“Christmas tree” or “fir tree” style, any suitable slot profile may beformed using this process including a simpler shape, such as a singlewidth slot, or a more complex shape, such as a rough slot which willeventually be machined to form a more detailed “Christmas tree” shape.

FIGS. 6A-6D are drawings of an embodiment of the cutting inserts 104according to the present disclosure. FIG. 6A is a drawing of a cuttingface of one embodiment of the cutting insert. FIG. 6B is a top view ofthe cutting insert. FIG. 6C is a left side view of the cutting insert ofFIG. 6A. FIG. 6D is a bottom view of the cutting insert. As shown inFIGS. 6A-6D, the insert may have a cutting portion 119 and the mountingportion 118. The mounting portion 118 may be secured within the cutterbody 102. The inserts 104 may also have a cutting face 126 or top faceand a backwall 128 or bottom face. The cutting face 126 may preferablybe substantially flat. The cutting face 126 may connect a left sidewall127 of the mounting portion 118 and a right sidewall 129 of the mountingportion 118 on one side of the insert, and the backwall 128 may connectthe left sidewall 127 and the right sidewall 129 on the other side ofthe insert. The cutting edge 110 may be formed at the junction of thecutting face 126, the left sidewall 127 and the right sidewall at thecutting portion 119 of the insert 104. The cutting edge may be formed atthe periphery of the cutting portion 119. The cutting face 126 mayintersect the left sidewall 127 and the right sidewall 129 atsubstantially right angles (e.g., 90°). The backwall 128 may form adovetail portion of the mounting portion 118 of the insert 104. Thebackwall 128 may be non-flat. For example, the backwall 128 may comprisea first portion 140 which may parallel the cutting face 126 and a secondportion 141 which intersects the first portion 140. The intersection ofthe first portion 140 and the second portion 141 may form a dovetailangle 144. As shown in FIG. 6D, the dovetail angle 144 may range from 1°to 20°, but may equal 10° degrees in a preferred embodiment. The secondportion 141 may not parallel the cutting face 126. The first portion 140of the backwall 128 may intersect the left sidewall 127 at substantiallya right angle. The second portion 141 of the backwall 128 may intersectthe right sidewall 129 at an angle greater than 90°.

According to various embodiments, the inserts 104 may include aclearance angle 142 under the cutting edge 110 and a dovetail portion,which may be formed from the first portion 140 and the second portion141 of the backwall 128, opposite of the cutting face 126. The clearanceangle 142 may extend rearward from the cutting edge. The clearance angle142 may extend rearward from the cutting portion 119 of the cutting edgeto the backwall 128 of the insert 104. The clearance angle 142 may beformed in the range of 4° to 20°. In one embodiment, the clearance angle142 may be 11°. In another embodiment, the clearance angle may be 6°.The clearance angle 142 may be formed to allow the cutting edge 110 tomove through the turbine disk 101 without binding up in the turbine disk101.

The dovetail portion may generally be located on the backwall 128 of theinsert 104 that may be adapted to engage a correspondingly shapeddovetail slot on the cutter body 102. The dovetail portion of the insert104 is shown in FIGS. 6B-6D and 8. A corresponding dovetail slot in thecutter body 102 may be formed. The dovetail slot in the cutter body 102may have a depth substantially equal to the mounting portion 118 of theinsert 104. The insert 104 may be placed between the wedge-like fastener106 and the cutter body 102 and may be retained in position in thatlocation.

FIGS. 7 and 8 illustrate aspects of the mechanism for securing each ofthe inserts 104 to the cutter body 102. FIG. 7 is a close-up of a sideview of the cutting insert 104 retained in the cutter body 102 by thewedge-like fastener 106. FIG. 8 is a close-up of a top view of theinsert 104 being retained in the cutter body 104 by the wedge-likeinsert 106. With reference to FIGS. 7 and 8, the cutting insert 104 maybe retained on the cutter body 102 by the wedge-shaped fastener 106. Asupport portion 120 of the cutter body 102 may support the backwall 128of the insert 104 opposite the cutting edge 110. The insert 104 may restupon an axially positioning surface 121. As the screw 108 securing thewedge-like fastener 106 to the cutter body 102 is tightened, thewedge-like fastener 106 and the insert 104 may interact to draw theinsert 104 securely and accurately into position on the cutter body 102.

As shown in FIG. 8, the insert 104 may be placed such that the cuttingface 126 faces the wedge-like fastener 106, and the backwall 128 facesthe dovetail portion of the slot in the cutter body 102. The insert 104may be secured in the cutter body 102 by tightening the wedge-likefastener 106 through use of the screw 108 securing the wedge-likefastener to the cutter body 102. Upon tightening the wedge-likefastener, the insert 104 may be drawn into the cutter body 102 andpositively located. The wedge-like fastener 106 may comprise an insertface 131, a body face 133, a right face 135 and a left face 137. Theinsert face 131 may engage the cutting face 126 of the insert, and thebody face 133 may engage a portion of the cutter body 102. The insertface 131 may connect the right face 135 and the left face 137. Theinsert face may intersect the right face 135 in substantially a rightangle and may intersect the left face 137 at an angle greater than 90°.The body face 133 may also connect the right face 135 and the left face137. The body face 133 may intersect both the right face 135 and theleft face 137 at angles less than 90°.

According to various embodiments, the screw 108 may extend from a holein the right side 135 of the wedge-like fastener through the left side137 of the wedge-like fastener 106 into the cutter body 102. As thescrew 108 is tightened, the wedge-like fastener may move along a pathdefined between the interface of the body face 133 and the portion ofthe cutter body. As the wedge-like fastener 106 moves along theinterface, the insert face 131 may be forced in a direction toward thecutting face 126 causing the backwall 128 to engage the dovetail portionof the cutter body 102. As the wedge-like fastener 106 is tightened, thedovetail shape on the backwall 128 and the corresponding slot in thecutter body 104 may allow easy and accurate installation of the inserts104 in the proper positions. The dovetail arrangement may also preventaxial movement of the insert 104 during the metal machining process.

The slots 116 which may be machined in turbine disks may be quitenarrow, for example, 0.5 inch or less, and therefore the inserts 104 mayneed to be strong and held firmly in the cutter body 102. The wedge-likefastener 106 included in the cutter body 102 may apply pressure to theinsert 104, thereby largely inhibiting or preventing radial movement. Asdiscussed above, the fastener 106 may be mounted in a slot in the cutterbody 102 with a screw 108 that may actuate the wedge portion positionedaxially to the cutter body 102. There may exist a gap 117 between thewedge-like fastener 106 and the slot in the cutter body. This gap 117may exist between the insert face 131 of the wedge-like fastener 106which contacts the insert 104 and the notch of the cutter body 102. Thisgap may be used to ensure that the wedge-like fastener 106 engages theinsert 104 when tightened and does not bind up on the cutter body 102thus preventing proper tightening of the insert 104. This arrangementmay simplify manufacture and improves rigidity of the cutter body 102since less material may be removed from the cutter body 102 in adirection radially inward from the periphery of the cutter body 102.Such a design may also provide, upon tightening of the screw 108, aforce on the insert 104 that draws the insert dovetail form back intothe corresponding dovetail slot on the cutter body 102, thus betterassuring proper location and positive retention. When the wedge-likefastener 106 is fully tightened, the insert 104 may be properly seatedand may be retained in a positive way such that axial movement may beprevented and destructive forces may be minimized. The wedge-likefastener 106 may be positioned to contact the cutting face 126 of theinsert 104, as shown in the attached figures, or alternatively tocontact the backwall 128 of the insert 104, and the dovetail could be onthe backwall 128 (as shown), the cutting face 126, or on both thebackwall 128 and the cutting face 126 of the cutting insert 104.

The periphery of the cutter body 102 may be formed with a shape similarto the cutting edge 110 on the inserts 104. This support portion 120 ofthe cutter body 102 may be formed in a similar shape to the insert 104,but may be slightly smaller in dimension. The support portion 120 mayprovide support for the cutting portion 119 of the inserts 104. Thewedge-like fastener 106 may be positioned radially inward from thecutting edge 110 portion of the insert 104 to allow full engagement ofthe cutting edge 110 during the machining operation. A suitable undercutmay be provided at the lower rear of the dovetail slot to help insureaccurate positioning of the insert 104 and allow ease of manufacture.

The cutting edge 110 shape of the insert 104 may be preferably acompound form having two or more widths, as discussed above and shown inFIG. 6A-6C. The cutting edge 110 may extend around the periphery of thecutting portion 119 of the insert 104. Although having two or morewidths may be a preferred embodiment, the cutting edge 110 may only haveone width. According to one embodiment, as shown in FIG. 6A, the cuttingedge 110 of the insert 104 may be preferably formed to have a primaryradius 146 at the tip of the insert 104 and may extend rearward from thetip at a desired width for rough cutting the base of the slot 116. Theremay be two secondary radii 152 a-b located at or near the intersectionof the cutting portion 119 and the mounting portion 118 of the insert104. The secondary radii 152 a-b may be found on opposing sides of thecutting edge 110. There may be preferably two outwardly extendingtertiary radii 148 a-b, or transition outwardly extending radii, at thepoint where the width between opposing sides of the cutting edge 110increases. These outwardly extending tertiary radii 148 a-b may be foundon opposing sides of the cutting edge 110. In addition, there may be twoinwardly extending tertiary radii 150 a-b, inwardly extending, at thepoint where the width of insert 104 corresponds to the desired rough cutwidth of more radially outward portions of the slot 116. The inwardlyextending tertiary radii 150 a-b may be found on opposing sides of thecutting edge 110, as shown in FIG. 6A. The outwardly extending tertiaryradius 148 a and the inwardly extending tertiary radius 150 a may belocated between the primary radius 146 and the secondary radius 152 a.Similarly, the outwardly extending tertiary radius 148 b and theinwardly extending tertiary radius 150 b may be located between theprimary radius 146 and the secondary radius 152 b.

The inserts 104 may be formed in the same manner, but may have variousshapes of cutting edges. According to a second embodiment, as shown inFIG. 6E, the cutting edge 210 may extend around the periphery of thecutting portion 219 of the insert 204. The cutting edge 210 may beformed to have at least one primary radius 246 a-b and may extendrearward from the tip at a desired width for rough cutting the base ofthe slot. In the embodiment shown in FIG. 6E, the insert has two primaryradii 246 a-b located at a tip of the insert 204. These primary radii246 a-b may be found on opposing sides of the cutting edge 210. Inaddition, there may exist two secondary radii 252 a-b, which may befound on opposing sides of the cutting edge 210. These secondary radii252 a-b may be found at or near the intersection of the cutting portion219 and a mounting portion 218.

In another embodiment, as shown in FIG. 6F, the cutting edge 310 mayextend around the periphery of the cutting portion 319 of the insert304. The cutting edge 310 of the insert 304 may be preferably formed tohave at least one primary radius 346 a-b at the tip of the insert 304and may extend rearward from the tip at a desired width for roughcutting the base of the slot. In the embodiment shown in FIG. 6F, theinsert has two primary radii 346 a-b located at a tip of the insert 304.There may be two secondary radii 352 a-b located at or near theintersection of the cutting portion 319 and the mounting portion 318 ofthe insert 304. The secondary radii 352 a-b may be found on opposingsides of the cutting edge 310. There may be preferably two outwardlyextending tertiary radii 348 a-b, or transition outwardly extendingradii, at the point where the width between the opposing sides of thecutting edge 310 increases. These outwardly extending tertiary radii 348a-b may be found on opposing sides of the cutting edge. In addition,there may be two inwardly extending tertiary radii 350 a-b, inwardlyextending, at the point where the width of insert 304 corresponds to amore radially outward portion of the slot. The inwardly extendingtertiary radii 350 a-b may be found on opposing sides of the cuttingedge 310, as shown in FIG. 6F.

Additionally, there may be two outwardly extending quaternary radii 349a-b at the point where the width between the opposing sides of thecutting edge 310 again increases. These outwardly extending quaternaryradii 349 a-b may be found on opposing sides of the cutting edge 310. Inaddition, there may be two inwardly extending quaternary radii 351 a-b,inwardly extending, at another point where the width of insert 304corresponds to a more radially outward portion of the slot. The inwardlyextending quaternary radii 351 a-b may be found on opposing sides of thecutting edge 310, as shown in FIG. 6F. The outwardly extending tertiaryradius 348 a and the inwardly extending tertiary radius 350 a may belocated between the primary radius 346 a and the outwardly extendingquaternary radii 349 a. Similarly, the outwardly extending tertiaryradius 348 b and the inwardly extending tertiary radius 350 b may belocated between the primary radius 346 b and the outwardly extendingquaternary radii 349 b. The outwardly extending quaternary radius 349 aand the inwardly extending quaternary radius 351 a may be locatedbetween the inwardly extending tertiary radius 350 a and the secondaryradius 352 a. Similarly, the outwardly extending quaternary radius 349 band the inwardly extending quaternary radius 351 b may be locatedbetween the inwardly extending tertiary radius 350 b and the secondaryradius 352 b.

Depending upon the rough groove form, the insert could be single-ended(as shown) or double-ended. The single-ended insert may only have onedovetail portion. The single-ended dovetail portion may be on the sideof the insert opposite the cutting edge. The double-ended insert mayhave two cutting edges on opposite ends of the insert and two dovetailportions to allow the insert to be turned over in the slotting cutter touse both cutting edges. Of course, modifications to the slotting cutterand different wedge-like fasteners may be required to accommodate thedouble-ended insert. For example, a reverse or opposite hand slottingcutter may be required to accommodate the double-ended insert. Inaddition, the wedge-like fastener may need to be fabricated to accountfor the dovetail on both ends of the double-ended insert. Anothermodification that may be required in adapting the slotting cutter foruse with a double-ended insert may be reducing the height of the axiallypositioning surface to accommodate the double-ended insert. There may becost advantages to using a double-ended insert.

According to various embodiments, advantages of the slotting cutter 100and inserts 104 may include the ability to completely rough machine theentire slot 110 in a turbine disk in one pass using one size or style ofinsert 104. Based on testing of the slotting cutter 100 and inserts 104,there appears to be no need to make multiple passes or to stock severalsizes or styles of inserts 104. As disclosed, the slotting cutter 100may be run at higher speeds and may have the rigidity important tomaintaining machining accuracy and extending insert 104 life.

According to various embodiments, the cutting inserts 104 may befabricated from a high strength whisker reinforced ceramic material. Forexample, WG-300® ceramic, available from Greenleaf Corporation,Saegertown, Pa., or any other suitable material may be used. The use ofceramic materials may allow the use of higher machining speeds. In fact,machining performance may be increased due to the higher machine speeds.By machining at higher speeds, the slots 116 may be cut moreefficiently, and the inserts 104 may wear much slower thus increasingthe life of the inserts 104. As insert 104 life increases, the need tostop the slotting cutter 100 from operating to change the worn inserts104 decreases. The inserts 104 may be made of other materials, such as,for example, cemented carbide or any other suitable material. Dependingupon the material used to fabricate the inserts 104, insert 104performance may be affected depending upon the material being cut. Forexample nickel-based superalloys, such as Alloy 718 (UNS N017718) andRene 95™ alloy, may be machined very efficiently, both in terms ofmaterial removal from the work piece and insert 104 wear, with an insert104 fabricated from WG-300® ceramic, but may not be machined efficientlyusing an insert 104 fabricated from cemented carbide.

A slotting cutter 100 according to the present disclosure has beenattached to a standard rotary face mill toolholder and has been used toperform numerous test cuts at various feed rates (e.g., the rate atwhich the slotting cutter advances through the cut) and at rotationalspeeds up to about 3000 RPM (i.e., about 7068 SFM). These tests includedmounting the set-up on a Kitamutra HX630 Horizontal Machining Center.The various test results are summarized in Table 1. The slotting cutter100 embodiment successfully rough machined up to 21 slots 116 in aturbine disk made of Rene 95 alloy having a hardness of 48-50 RC withoutsignificant cutting insert 104 wear. Also, the rough slots 116 producedin that test were machined in the disk at more than three times the feedrate and more than three times faster than a previous slotting cutterdesign the present inventor had produced and tested, and the chips fromthe machining operation were easy to control and handle. IPM is theinches per minute of the travel of the slotting cutter in the feeddirection.

TABLE 1 Climb or Insert Conventional Slots Grade SFM RPM IPM CutProduced Comments WG300 4005 1700 61.2 Conventional 4 Insert 431903,4712 2000 72 8 NP Horizontal Mill WG300 4712 2000 54 Conventional 13 Insert 431903, NP Horizontal Mill WG300 4712 2000 36 Conventional 12 Insert 431949, NP Horizontal Mill WG300 4712 2000 90 Conventional 12 (6full Insert 431949, and 6 NP Horizontal shallow) Mill WG300 5654 2400108 Conventional 1 Insert 431903, 6126 2600 117 1 Kitamura Mill, 65972800 127 1 inserts edge 7068 3000 135 1 broke down faster, one insertchipped out, feed reduced at start of cut WG300 2827 1200 18Conventional 8, with 6 Insert 431903, inserts in Kitamura Mill, cutterfeed reduced at start of cut WG300 2827 1200 54 Conventional 21  Insert431949, Kitamura Mill, feed reduced at start of cutInsert 431903 used in the above testing has a clearance angle of 6°.Insert 432949 used in the above testing has a clearance angle of 11°.

According to various embodiments, additional advantages of the slottingcutter 100 may include the ability to provide more inserts 104 in thesame diameter cutter body 102. In one example, 18 inserts 104 were usedin the same diameter cutter 102 that had been limited to 12 inserts 104in an alternate design. By using more inserts in the same diametercutter, insert 104 wear may be greatly reduced. More inserts 104 mayallow for faster machining, which may result in higher material removalrates. Other advantages of the use of this slotting cutter 100 designdescribed herein may include increased cutter rigidity, positive insert104 retention, better accuracy, longer insert 104 life, and ease ofmanufacture. Various similar insert 104 forms, shapes, and/or sizescould be used in the same cutter body 102.

Although the foregoing description has necessarily presented only alimited number of embodiments, those of ordinary skill in the relevantart will appreciate that various changes in the articles and methods andother details of the examples that have been described and illustratedherein may be made by those skilled in the art, and all suchmodifications will remain within the principle and scope of the presentdisclosure as expressed herein and in the appended claims. For example,although the present disclosure has necessarily only presented a limitednumber of embodiments according to the present disclosure, it will beunderstood that the present disclosure and associated claims are not solimited. Those having ordinary skill will readily identify additionaldesigns and may design and build additional designs along the lines andwithin the spirit of the necessarily limited number of embodimentsdiscussed herein. It is understood, therefore, that the presentinvention is not limited to the particular embodiments disclosed orincorporated herein, but is intended to cover modifications that arewithin the principle and scope of the invention, as defined by theclaims. It will also be appreciated by those skilled in the art thatchanges could be made to the embodiments above without departing fromthe broad inventive concept thereof.

The examples presented herein are intended to illustrate potential andspecific implementations of the embodiments. It can be appreciated thatthe examples are intended primarily for purposes of illustration forthose skilled in the art. No particular aspect or aspects of theexamples is/are intended to limit the scope of the describedembodiments.

It is to be understood that the figures and descriptions of theembodiments have been simplified to illustrate elements that arerelevant for a clear understanding of the embodiments, whileeliminating, for purposes of clarity, other elements. Because manymachining techniques are well known in the art and because they do notfacilitate a better understanding of the embodiments, a discussion ofsuch techniques is not provided herein.

While various embodiments have been described herein, it should beapparent that various modifications, alterations and adaptations tothose embodiments may occur to persons skilled in the art withattainment of at least some of the advantages. The disclosed embodimentsare therefore intended to include all such modifications, alterationsand adaptations without departing from the scope of the embodiments asset forth herein.

1. An insert comprising: a cutting edge, wherein the cutting edge isformed at a junction of a cutting face, a left sidewall and a rightsidewall, and wherein the cutting edge forms a narrow outer end at a tipof the insert and a larger width region at a distance inward from thenarrow outer end; at least one primary radius, wherein the at least oneprimary radius is located at the tip of the insert; at least twosecondary radii, wherein the at least two secondary radii are located onopposite sides of the cutting edge near a mounting portion of theinsert; at least two outwardly extending tertiary radii, wherein the atleast two outwardly extending tertiary radii are located on oppositesides of the cutting edge between the at least one primary radius andthe at least two secondary radii; at least two inwardly extendingtertiary radii, wherein the at least two inwardly extending tertiaryradii are located on opposite sides of the cutting edge between the atleast two outwardly extending tertiary radii and the at least twosecondary radii; and a clearance angle, wherein the clearance angleextends rearward from the cutting edge.
 2. The insert of claim 1,wherein the insert is fabricated from a ceramic material.
 3. The insertof claim 2, wherein the insert is fabricated from a high strengthwhisker reinforced ceramic material.
 4. The insert of claim 3, whereinthe high strength whisker reinforced ceramic material is WG-300®ceramic.
 5. The insert of claim 1, wherein the mounting portion furthercomprises: a backwall, wherein the backwall comprises a first portionand a second portion, and wherein the first portion and the secondportion form a dovetail portion of the mounting portion; a cutting face,wherein the cutting face is located on the opposite side of the mountingportion from the backwall; a left sidewall, wherein the left sidewallconnects the backwall and the cutting face; and a right sidewall,wherein the right sidewall connects the backwall and the cutting face.6. The insert of claim 5, wherein the insert is configured to beretained upon a cutter body using a wedge-like fastener which is securedto the cutter body using a screw.
 7. The insert of claim 6, wherein theinsert is configured to be secured between the wedge-like fastener and aretaining slot in the cutter body.
 8. The insert of claim 7, wherein thedovetail portion of the insert corresponds to a dovetail surface in thecutter body.
 9. The insert of claim 8, wherein the dovetail portion ofthe insert contacts the corresponding dovetail surface of the retainingslot in the cutter body to be securely retained within the retainingslot of the cutter body by tightening the screw securing the wedge-likefastener to the cutter body thus causing the wedge like fastener toengage a surface of the insert.
 10. The insert of claim 1, furthercomprising: at least two outwardly extending quaternary radii, whereinthe at least two outwardly extending quaternary radii are located onopposite sides of the cutting edge between the at least two inwardlyextending tertiary radii and the at least two secondary radii; and atleast two inwardly extending quaternary radii, wherein the at least twoinwardly extending quaternary radii are located on opposite sides of thecutting edge between the at least two outwardly extending tertiary radiiand the at least two secondary radii.
 11. The insert of claim 1, whereinthe insert is configured to cut a slot depth of ¾ inch.
 12. The insertof claim 1, wherein the insert is configured to cut a slot width of ½inch.
 13. A slotting cutter assembly for machining slots in metallicparts, the slotting cutter assembly comprising: a plurality of insertscomprising: a cutting edge, wherein the cutting edge is formed at ajunction of a cutting face, a left sidewall and a right sidewall, andwherein the cutting edge forms a narrow outer end at a tip of the insertand a larger width region at a distance inward from the narrow outerend; at least one primary radius, wherein the at least one primaryradius is located at the tip of the insert; at least two secondaryradii, wherein the at least two secondary radii are located on oppositesides of the cutting edge near a mounting portion of the insert; atleast two outwardly extending tertiary radii, wherein the at least twooutwardly extending tertiary radii are located on opposite sides of thecutting edge between the at least one primary radius and the at leasttwo secondary radii; at least two inwardly extending tertiary radii,wherein the at least two inwardly extending tertiary radii are locatedon opposite sides of the cutting edge between the at least two outwardlyextending tertiary radii and the at least two secondary radii; and aclearance angle, wherein the clearance angle extends rearward from thecutting edge; and a cutter body comprising: a plurality of retainingslots, wherein the plurality of retaining slots are configured toreceive the plurality of inserts; and a plurality of support portions,wherein the support portions are disposed on one end of the retainingslot, and wherein the support portion provides support for the insert.14. The slotting cutter assembly of claim 13, wherein the insert isfabricated from a ceramic material.
 15. The slotting cutter assembly ofclaim 14, wherein the insert is fabricated from a high strength whiskerreinforced ceramic material.
 16. The slotting cutter assembly of claim15, wherein the high strength whisker reinforced ceramic material isWG-300® ceramic.
 17. The slotting cutter assembly of claim 13, whereinthe mounting portion of the insert further comprises: a backwall,wherein the backwall comprises a first portion and a second portion, andwherein the first portion and the second portion form a dovetail portionof the mounting portion; a cutting face, wherein the cutting face islocated on the opposite side of the mounting portion from the backwall;a left sidewall, wherein the left sidewall connects the backwall and thecutting face; and a right sidewall, wherein the right sidewall connectsthe backwall and the cutting face.
 18. The slotting cutter assembly ofclaim 13, wherein the insert is configured to be retained upon thecutter body using a wedge-like fastener which is secured to the cutterbody using a screw.
 19. The slotting cutter assembly of claim 18,wherein the insert is configured to be secured between the wedge-likefastener and a dovetail surface formed in retaining slot.
 20. Theslotting cutter assembly of claim 19, wherein the dovetail portion ofthe insert corresponds to the dovetail surface in the cutter slot. 21.The slotting cutter assembly of claim 20, wherein the dovetail portionof the insert contacts the corresponding dovetail surface of theretaining slot in the cutter body to be securely retained within theretaining slot of the cutter body by tightening the screw securing thewedge-like fastener to the cutter body thus causing the wedge likefastener to engage a surface of the insert.
 22. The slotting cutterassembly of claim 13, wherein the plurality of inserts furthercomprises: at least two outwardly extending quaternary radii, whereinthe at least two outwardly extending quaternary radii are located onopposite sides of the cutting edge between the at least two inwardlyextending tertiary radii and the at least two secondary radii; and atleast two inwardly extending quaternary radii, wherein the at least twoinwardly extending quaternary radii are located on opposite sides of thecutting edge between the at least two outwardly extending tertiary radiiand the at least two secondary radii.
 23. The slotting cutter assemblyof claim 13, wherein the insert is configured to cut a slot depth of ¾inch.
 24. The slotting cutter assembly of claim 13, wherein the insertis configured to cut a slot width of ½ inch.